Downgrade npm version (temporary) and address node-gyp symlink issue

• node-gyp symlink issue: Addressed a conflict caused by node-gyp internally linking to an absolute path symlink for python3, which can clash with multiple Python environments (see discussion: Notarization and staple succeeds but app is not able to be verified by Apple electron-userland/electron-builder#7755).

Fixes:

• Temporary npm downgrade: As a temporary workaround to the node-gyp issue, we've pinned npm to version 8.16.0 (see related issue: Can't open OpenMTP #367).

Important Note:

We are actively investigating a more permanent solution that doesn't require an npm downgrade. We'll update this issue with a long-term fix soon.